Orchard Park

Stormwater runoff is an issue affecting the entire Omaha region. In neighborhoods long developed, or in new developments, increases in the amount of paved or "impervious" areas increase the amount of stormwater runoff trying to enter drainage inlets and our streams. In addition, increases in the amount of traffic increases the amount of pollutants that are carried by stormwater runoff, especially the first one-half inch of runoff that enters our streams and water bodies. This results in streams that are rapidly eroding, creating dangerous conditions and destroying property, and poor water quality that creates unpleasant environments near streams and lakes.

In 2008 alone, we have seen dramatic damage to Omaha's streams.

To help control these conditions, Olsson Associates designed stormwater best management practices (BMPs) to collect some of the stormwater runoff before it enters the storm sewers and our streams, allowing it to be detained for a short period to infiltrate into the ground. In doing so, the runoff is also cleansed of many of its pollutants. These stormwater BMPs involve shallow basins vegetated with native plants that perform best in filtering the water and allowing it to infiltrate into the ground. These BMPs take many forms, from larger detention basins, to buffer areas along streams, to smaller treatment units such as bioretention cells and rain gardens.

The BMPs include the following:

BMP No. 1, located adjacent to the Orchard Park parking lot, is a bioretention garden. This garden initially functions as a bioretention cell that temporarily detains stormwater, but then allows it to drain through a sand and compost filter into subdrains. This process slows the movement of water toward the stream, promotes infiltration into the soil, and filters and cleanses pollutants from the stormwater runoff.

It is called a garden because it includes native grasses and flowers to provide an ornamental amenity to the park. Stormwater typically collects rapidly in the parking lot, ponding in the circle area and on the south edge of the lot. The curbs will be cut to allow water to drain to depression areas where it will collect. Most of the collected water will infiltrate into the soil, although some will drain to an outlet closer to the stream. The garden will be planted with native grasses, such as little bluestem, buffalo grass, switch grass, Indian grass, and big bluestem, and native vegetation, such as prairie blazing star, wild bergamont, yellow coneflowers, black-eyed susans, New England aster, and butterfly milkweed.

BMP No. 2 is located in the north portion of the park, also along North 66th Street. It is designed to capture stormwater runoff from the street before it enters the storm sewer system. This bioretention garden was built between the sidewalk and the curb, and it connects to a larger cell on the east side of the sidewalk. This larger cell allows excess water coming from the street to be treated while it infiltrates into the ground. Subsurface drains slowly discharge some of the infiltrating stormwater to Cole Creek.

The two cells are connected by pipes below the sidewalk. BMP No. 2, the larger of the two bioretention gardens, will be connected to a walking trail constructed near Cole Creek and include a walking path around its perimeter. The biorentention garden is planted with native vegetation and native grasses.

Signs will be placed near both bioretention gardens to inform people about the benefits of the gardens and to help identify plants. When completed, these BMPs should provide aesthetic amenities to Orchard Park, in addition to beneficial stormwater management.